The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the inventors hereof, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
The disclosed technology relates to instantaneous noise estimation of an audio signal and is applicable to audio processing systems, such as speech recognition or enhancement systems. In speech processing, a noisy audio signal often includes a superposition of a raw speech signal and a noise signal. In order to accurately isolate and process the raw speech signal, the noise signal must be properly estimated so that it can be removed. Noise estimation techniques should be able to quickly and accurately provide an estimate for the noise, and need to be able to do so dynamically as the noise in a signal changes. Early noise estimation techniques, such as voice activity detection, tracked the presence of speech in the audio signal. During periods without speech, the noise estimate is approximated as the instantaneous signal power. During periods of speech, the noise estimate is not updated.